Hi,
I am a new member and I'm generally at best low average with my smoking. But I did work offshore in Alaska for over 10 years in the seafood industry and have cooked a lot of salmon, halibut, and spot prawns. As I used to get a lot of it comped. And sorry Alaska but think Atlantic cod is better than Pacific Cod.
So general tips that have worked out for me.
King is my favorite to smoke. They are bigger with thicker fillets and the highest in fat content. Reds second. But also note pinks and chums good when processed directly after catching. Faroe Island is the only farmed salmon I like and I don't tell any of my friends still working in Alaska that I sometimes buy it. But here in the wilds of upstate New York it's about half as much as wild salmon.
The best way to defrost a frozen filet is to let it sit in your refrigerator until defrosted. Which might take 2 days.
To extent you have whole frozen fish (in the round is industry term that describes that) or head and gut, use carcass to make stock.
Do remove pin bones. A tweezer made for this purpose tends to leave less of a divot in the salmon than using needle nose pliers. Chef Knives To Go has a cheap pair of tweezers for maybe 12 or 15.
A really thick fillet brines more evenly if you remove the skin first. There are a great many YouTube videos about how to do this, but it's pretty simple. All you need is a flat cutting surface and a really sharp fillet knife. Fun fact. The Japanese who are super big on seafood have a special knife, called a deba, only beveled on one side and used exclusively for skinning and breaking down fish.
If you remove the skin first you can roast it in the oven until a bit crispy and use it in assorted Japanese Korean Chinese etc. seafood dishes.
For hot smoking a wet brine works better than a dry brine. Brine for 18 to 24 hours then a full 8 hour day uncovered in refrigerator. Which dries the surface forms a barrier and helps avoid white stuff.
Hot smoking is best at a relatively cool temperature. I do it at 200F but some people say 150F is better. Although I might worry about it food safety cooking it at that low temperature.
You absolutely want to avoid the white stuff. Albumin. Any salmon I've ever had where that stuff was squeezed out was porked. Meaning dry. It's avoided by wet brine followed by drying out in refrigerator, useing relatively low temperature to cook, and glazes.
Which is also why my favorite way to cook salmon is in a low oven (250F) skin side up on a bed of butter slices until it gets to about 120 to 125F. You can tell it's done when the skin peels off easily. That's good with some fresh herb oil made with a blender and garlic mashed potatoes. And if I have paid 38 a pound for a fresh King fillet I know the low oven technique has a very low possibility of my screwing it up.
And while digressing into cooking versus smoking would suggest almost all fish and shellfish benefit from an hour or two in a 5 percent brine before cooking.
My favorite salmon brines and glazes use maple syrup.
For cold smoking it's safer to use a pink salt cure. Having said that, it's mainly winter here in upstate New York. If the outside temperature is below freezing then I can keep the cold smoking chamber temperature below freezing.
For winter cold smoking I just pour some pellet smoker pellets into a pan and use a propane torch to light some of them so they burn like a fuse. And then put that smoking pan along with the fillets inside a smoker and let it go for 2 hours or so.
I hope that was helpful.